Bleed valve module with position feedback and cooling shroud

ABSTRACT

A bleed valve control system for mounting to a support structure adjacent to a fan air plenum within an aircraft includes a bleed valve module, a pneumatic valve controller, and a fan air duct. The bleed valve module includes a pipe, a plurality of bleed valves connected to the pipe, and a plurality of pneumatic actuators connected to the bleed valves. The pneumatic valve controller includes a plurality of electrical control elements and a cooling shroud. The cooling shroud is attached to the pipe and at least partially surrounds the plurality of electrical control elements. The fan air duct connects the cooling shroud to the fan air plenum such that fan air flows through the cooling shroud to cool the plurality of electrical control elements.

BACKGROUND

The present invention relates to aircraft air management systems. Inparticular, the invention relates to bleed air systems for supplyingcompressed air to an aircraft air management system.

Aircraft air management systems supply bleed air to a variety ofaircraft systems, such as an environmental control system to maintainaircraft cabin air pressures and temperatures within a target range forthe safety and comfort of aircraft passengers, anti-icing systems,air-driven pumps, etc. This is done through the use of compressed airtaken from two compressor stages (bleed air) of at least one of thebypass turbine engines propelling the aircraft. Each of the two airpressures available from the compressor (intermediate pressure (IP) andhigh pressure (HP)) are directed to the air management system throughpressure lines or plenums. A pneumatic valve controller operates aseries of pneumatically operated bleed valves in response to electroniccontrol signals from the air management system to control the relativeflows of IP and HP compressed air flowing to the air management system.Air pressure in the pressure lines is measured by at least one pressuresensor which provides this information to air management system. The airmanagement system uses the air pressure information along with otherinformation from around the aircraft to direct the pneumatic valvecontroller to provide the desired bleed air flow to the air managementsystem.

The bleed valves, pressure sensor, and pneumatic valve controller areexposed to extreme conditions. These components operate near thecompressor of the bypass turbine engine, in an environment of extremevibration. In addition, the compressed air is extremely hot, in excessof 600 degrees Fahrenheit. This extreme heat and vibration are majorfactors leading to failure of these components.

SUMMARY

An embodiment of the present invention concerns a bleed valve controlsystem for mounting to a support structure adjacent to a fan air plenumwithin an aircraft. The system includes a bleed valve module, apneumatic valve controller, and a fan air duct. The bleed valve moduleincludes a pipe, a plurality of bleed valves connected to the pipe, anda plurality of pneumatic actuators connected to the plurality of bleedvalves. The pipe contains a flow of bleed air and includes a pluralityof inlets and an outlet. The plurality of bleed valves controls the flowof bleed air in the pipe. The plurality of pneumatic actuators actuatethe plurality of bleed valves. The pneumatic valve controller includes aplurality of electrical control elements and a cooling shroud. Thecooling shroud is attached to the pipe and at least partially surroundsthe plurality of electrical control elements. The fan air duct connectsthe cooling shroud to the fan air plenum such that fan air flows throughthe cooling shroud to cool the plurality of electrical control elements.

Another embodiment of the present invention concerns a method forenhancing the reliability of a bleed valve control system, the methodincluding the steps of: attaching a bleed valve module comprising aplurality of pneumatically actuated bleed valves to a support structureadjacent to a fan air plenum; connecting a pneumatic valve controller tothe bleed valves by pneumatic control lines; and cooling the pneumaticvalve controller with fan air.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side schematic view of a bypass turbine engine and pylonincorporating a bleed valve control system of the present invention.

FIG. 2 is a more detailed side schematic view of a portion of the bypassturbine engine and pylon of FIG. 1 illustrating an embodiment of a bleedvalve control system of the present invention.

FIG. 3 is a more detailed side schematic view of a portion of the bypassturbine engine and pylon of FIG. 1 illustrating another embodiment of ableed valve control system of the present invention.

FIG. 4 is a more detailed side schematic view of a portion of the bleedvalve control system of FIG. 3.

DETAILED DESCRIPTION

Conventional implementations of bleed valves, bleed air system sensorsand pneumatic valve controllers to provide bleed air for aircraft airmanagement systems leave these components susceptible to damage fromvibration and high temperatures. The present invention includes avibration-isolated bleed valve module to isolate bleed valves fromharmful vibration effects. In addition, by positioning the bleed valvemodule near a fan air plenum, the present invention protectstemperature-sensitive electrical control elements, such as torque motorsand pressure sensors, with a cooling flow of fan air. By reducing theeffects of heat and vibration, the reliability and lifespan of the bleedvalve control system components is enhanced. The present invention alsopermits locating temperature-sensitive electrical control elements,including valve position sensors, close to the bleed valves. Thisprovides for closely coupled feedback monitoring of the bleed valvepositions, providing better control with reduced control oscillations.Reducing control oscillations further enhances component reliability andlifetime by reducing the use of the bleed valves, which reduces the wearon the bleed valves.

FIG. 1 is a side schematic view of a bypass turbine engine and pylonincorporating a bleed valve control system of the present invention.FIG. 1 shows aircraft propulsion system 10 attached to aircraft wing 12and includes bypass turbine engine 14 and pylon 16. Bypass turbineengine 14 includes fan 18, turbine engine shaft 20, compressor 22,combustor 23, turbine 24, exhaust nozzle 26, intermediate pressure bleedair line 28, high pressure bleed air line 30 and engine mount beam 31.Pylon 16 includes fan air plenum 32, bleed air conditioning system 34,and cooled bleed air line 36.

Pylon 16 connects bypass turbine engine 14 at engine mount beam 31 towing 12. Compressor 22 connects fan 18 and combustor 23. Combustor 23connects compressor 22 and turbine 24. Exhaust nozzle 26 is attached toturbine 24. Turbine engine shaft 20 is connected to fan 18, compressor22, and turbine 24. Intermediate pressure bleed air line 28 and highpressure bleed air line 30 are attached to stages of compressor 22providing air of intermediate pressure and high pressure, respectively.Intermediate pressure bleed air line 28 and high pressure bleed air line30 are also attached to bleed air conditioning system 34 in pylon 16.Fan air plenum 32 is a rigid-walled duct and extends from bypass turbineengine 14, through engine mount beam 31, bleed air conditioning system34, and out pylon 16. Cooled bleed air line 36 extends from bleed airconditioning system 34 through pylon 16 to wing 12 and on to the varietyof aircraft systems for which the aircraft air management systemsupplies bleed air (not shown).

In operation, air is compressed in stages by compressor 22 and ignitedwith fuel in combustor 23 to produce rapidly expanding gasses that driverotation in turbine 24. The expanding gasses exit exhaust nozzle 26providing a portion of the engine thrust. Turbine 24 rotates attachedturbine engine shaft 20, providing power for the compression of air incompressor 22 and for the rotation of fan 18. Fan 18 rotates to providea flow of fan air (F) through bypass turbine engine 14. The flow of fanair exiting bypass turbine engine 14 near nozzle 26 provides the balanceof the engine thrust. A portion of the fan air flows into fan air plenum32 for use by bleed air conditioning system 34. Intermediate pressurebleed air line 28 and high pressure bleed air line 30 direct air fromthe intermediate pressure and high pressure stages, respectively, ofcompressor 22 to bleed air conditioning system 34. Bleed airconditioning system 34 uses intermediate pressure bleed air provided byintermediate pressure bleed air line 28, high pressure bleed airprovided by high pressure bleed air line 30, and fan air flow providedby fan air plenum 32 to deliver cooled bleed air to the air managementsystem through cooled bleed air line 36 at a temperature and pressurerequired by the air management system to supply bleed air to a varietyof aircraft systems.

FIG. 2 is a more detailed side schematic view of a portion of the bypassturbine engine and pylon of FIG. 1 illustrating an embodiment of a bleedvalve control system of the present invention. FIG. 2 shows bleed airconditioning system 134 including fan air plenum 132, precooler 138,un-cooled bleed air line 140, intermediate pressure check valve 142, andbleed valve control system 143. Bleed valve control system 143 includesbleed valve module 144, pneumatic valve controller 146, pneumaticcontrol lines 148 a-148 c, pneumatic supply line 150, and bleed airpressure impulse lines 151 a-151 b. Bleed valve module 144 includes pipe152, vibration isolating element 154 (two shown), first bleed valve 156a, second bleed valve 156 b, and third bleed valve 156 c, pneumaticactuators 158 a-158 c, first bleed valve module inlet 160 a, secondbleed valve module inlet 160 b, and bleed valve module outlet 160 c.Pneumatic valve controller 146 includes bleed air pressure sensors 162a-162 b and torque motors 164 a-164 c.

Pipe 152 of bleed valve module 144 connects to high pressure bleed airline 30 at bleed valve module connection 160 a, intermediate pressurebleed air line 28 at bleed valve module connection 160 b, and un-cooledbleed air line 140 at bleed valve module connection 160 c. Intermediatepressure check valve 142 is connected to bleed air line 28. Precooler138 connects un-cooled bleed air line 140 to cooled bleed air line 36.Precooler 138 is an air-to-air heat exchanger connected to fan airplenum 132 such that there is efficient heat transfer between the bleedair flow through precooler 138 and the fan air flow (F) throughprecooler 138, without mixing of the bleed air flow and the fan airflow. Fan air plenum 132 is a rigid-walled duct and extends from bypassturbine engine 14, through engine mount beam 31, bleed air conditioningsystem 134, and out pylon 16.

Vibration isolating elements 154 connect bleed valve module 144 to asupport structure, for example, engine mount beam 31 as illustrated inFIG. 2, an internal structural framework (not shown) within pylon 16, ora mechanical support (not shown) for a rigid-walled duct, for example,fan air plenum 132. Bleed valves 156 a-156 c are connected to pipe 152such that bleed valve 156 a (High Pressure Valve) controls the flow ofbleed air (B) from high pressure bleed air line 30 into pipe 152, bleedvalve 156 b (Pressure Regulating Valve) controls the flow of bleed airthrough pipe 152 to un-cooled bleed air line 140, and bleed valve 156 c(Overpressure Valve) provides overpressure control between bleed valve156 b and un-cooled bleed air line 140. Pneumatic actuators 158 a-158 care attached to bleed valves 156 a-156 c to actuate bleed valves 156a-156 c.

Fan air plenum 132 is as described in reference to FIG. 1 for fan airplenum 32, but with the additional feature that pneumatic valvecontroller 146 is located within fan air plenum 132. Pneumatic controllines 148 a-148 c connect torque motors 164 a-164 c of pneumatic valvecontroller 146 to pneumatic actuators 158 a-158 c. Pneumatic supply line150 connects pneumatic valve controller 146 to a supply of pressurizedair, for example, pipe 152 between bleed valve 156 a and bleed valvemodule connection 160 a, which supplies high pressure air. The use ofhigh pressure air permits the use of smaller pneumatic actuators 158a-158 c. If desired for compatibility with torque motors 164 a-164 c,the supply of pressurized air may be cooled by a heat exchanger cooledby a fan air flow (not shown). Bleed air pressure impulse lines 151a-151 b connect bleed air pressure sensors 162 a-162 b to pipe 152 suchthat bleed air pressure sensor 162 a (High Stage Pressure Sensor) sensespressure in pipe 152 between bleed valve 156 a and bleed valve 156 b,and bleed air pressure sensor 162 b (Manifold Pressure Sensor) sensespressure in pipe 152 between bleed valve 156 b and bleed valve 156 c.Torque motors 164 a-164 c and bleed air pressure sensors 162 a-162 b areelectrically connected to a bleed system controller (not shown).

In operation, bleed air conditioning system 134 supplies cooled bleedair at a desired pressure in response to electronic control signals fromthe bleed system controller directed to torque motors 164 a-164 c ofpneumatic valve controller 146. Torque motors 164 a-164 c permit aportion of supply air from pneumatic supply line 150 to pressurizepneumatic control lines 148 a-148 c sufficiently to cause pneumaticactuators 158 a-158 c to open or close bleed valves 156 a-156 c asneeded to achieve the bleed air pressure required by the air managementsystem. For example, when bleed air is desired at pressures less thanthat of intermediate pressure bleed air line 28, torque motor 164 amodulates the supply air from pneumatic supply line 150 to pressurizepneumatic control line 148 a such that pneumatic actuator 158 a closesbleed valve 156 a, preventing high pressure air from flowing throughbleed valve module 144. Bleed air pressure is provided by intermediatepressure bleed air line 28 and controlled by modulating bleed valve 156b by torque motor 164 b via pneumatic control line 148 b and pneumaticactuator 158 b. When bleed air pressures required by the bleed systemcontroller exceed the air pressure available from intermediate pressurebleed air line 28, electronic control signals are sent to torque motor164 a to modulate the supply air to pneumatic actuator 158 a viapneumatic control line 148 a to open bleed valve 156 a. Opening pressurebleed valve 156 a produces pressure in pipe 152 that is higher than thatin intermediate pressure bleed air line 28, causing intermediatepressure check valve 142 to close. Bleed air pressure is provided byhigh pressure bleed line 30 and controlled by modulating bleed valve 156b by torque motor 164 b via pneumatic control line 148 b and pneumaticactuator 158 b. Should a failure in occur in the operation of bleedvalves 156 a-156 b, the bleed system controller signals torque motor 164c to modulate the supply air to pneumatic actuator 158 c via pneumaticcontrol line 148 c to close bleed valve 156 c and protect systemsdownstream of bleed valve module 144. Bleed air pressure sensors 162a-162 b provide bleed air pressure information to the bleed systemcontroller such that the bleed system controller can determine theelectronic control signals to send to torque motors 164 a-164 c toachieve the desired bleed air pressure from bleed air conditioningsystem 134.

Un-cooled bleed air flows from bleed valve module 144 into un-cooledbleed air line 140 and into precooler 138. The bleed air is cooled as itflows through precooler 138 by heat transfer to fan air also flowingthrough precooler 138. The heat transfer is by conduction through a heatexchange surface of relatively large area, and by convection to and fromthe heat exchange surface by the bleed air flow and the fan air flow,respectively. At no point in precooler 138 do the bleed air and fan airflows mix. The cooled bleed air flows from precooler 138 into cooledbleed air line 36 and on to the variety of aircraft systems for whichthe aircraft air management system supplies bleed air (not shown).

As noted above, bleed valves 156 a-156 c and pneumatic actuators 158a-158 c are all attached to pipe 152 of bleed valve module 144. Aplurality of vibration isolating elements 154 connect bleed valve module144 to a support structure, as described above, to isolate pipe 152 andall components connected to pipe 152 from vibration. This vibrationisolation serves to enhance the reliability of the components connectedto pipe 152. Vibration isolating element 154 is any type of vibrationisolating device, for example, an elastomeric material, damped spring,or a magneto-rheological fluid.

The modular nature of bleed valve module 144 also permits fast efficientreplacement of bleed valves 156 a-156 c and pneumatic actuators 158a-158 c all at one time. Bleed valve module 144 can be removed and a newbleed valve module 144 installed quickly to help minimize aircraftdowntime. This modularity also permits fast and efficient replacement ofindividual bleed valves 156 a-156 c and pneumatic actuators 158 a-158 conce bleed valve module 144 is removed.

Reliability of pneumatic valve controller 146 is enhanced by the coolingprovided from the flow of fan air past pneumatic valve controller 146within fan air plenum 132. Temperature-sensitive electrical controlelements, such as torque motors 164 a-164 c and bleed air pressuresensors 162 a-162 c, within pneumatic valve controller 146 are cooled,thereby enhancing their reliability. The performance of pneumaticallycontrolled systems degrades with longer pneumatic control line lengths.By locating bleed valve module 144 proximate fan air plenum 132,pneumatic valve controller 146 is located within fan air plenum 132while keeping pneumatic control lines 148 a-148 c relatively short.

The embodiment describe in reference to FIG. 2 enhances the reliabilityof bleed valves 156 a-156 c and pneumatic actuators 158 a-158 c byisolating these components from harmful vibration effects. In addition,by positioning bleed valve module 144 near fan air plenum 132, thisembodiment protects temperature-sensitive electrical control elements,such as torque motors 164 a-164 c and bleed air pressure sensors 162a-162 c, with a cooling flow of fan air. By reducing the effects of heatand vibration, the embodiment of FIG. 2 enhances the reliability andlifespan of the bleed valve control system components. Finally, themodular design of bleed valve module 144 enhances serviceability to helpminimize aircraft downtime.

FIG. 3 is a more detailed side schematic view of a portion of the bypassturbine engine and pylon of FIG. 1 illustrating another embodiment of ableed valve control system of the present invention. FIG. 3 shows bleedair conditioning system 234 including fan air plenum 232, precooler 238,un-cooled bleed air line 240, intermediate pressure check valve 242, andbleed valve control system 243. Bleed valve control system 243 includesbleed valve module 244, pneumatic control lines 248 a-248 c, pneumaticvalve controller 270, and fan air duct 272. Bleed valve module 244includes pipe 252, vibration isolating element 254 (two shown), bleedvalves 256 a-256 c, pneumatic actuators 258 a-258 c, and bleed valvemodule connections 260 a-260 c. FIG. 4 is a more detailed side schematicview of pneumatic valve controller 270 of bleed valve control system 243of FIG. 3. As shown in FIG. 4, pneumatic valve controller 270 includesbleed air pressure sensors 262 a-262 b, torque motors 264 a-264 c,pneumatic supply line 250, valve position sensors 274 a-274 c, andcooling shroud 276. Valve position sensors 274 a-274 c are any type ofelectro-mechanical sensor for detecting a change in position of anobject, for example, a rotary variable differential transformer or alinear variable differential transformer. Bleed air pressure sensors 262a-262 b, torque motors 264 a-264 c, and valve position sensors 274 a-274c are electrical control elements. Electrical control elements are thecomponents of bleed valve control system 243 most susceptible to failuredue to prolonged exposure to high temperatures.

Considering FIG. 3 and FIG. 4 together, pipe 252 of bleed valve module244 connects to high pressure bleed air line 30 at bleed valve moduleconnection 260 a, intermediate pressure bleed air line 28 at bleed valvemodule connection 260 b, and un-cooled bleed air line 240 at bleed valvemodule connection 260 c. Intermediate pressure check valve 242 isconnected to bleed air line 28. Precooler 238 connects un-cooled bleedair line 240 to cooled bleed air line 36. Precooler 238 is an air-to-airheat exchanger connected to fan air plenum 232 such that there isefficient heat transfer between the bleed air flow through precooler 238and the fan air flow (F) through precooler 238, without mixing of thebleed air flow and the fan air flow. Fan air plenum 232 is arigid-walled duct and extends from bypass turbine engine 14, throughengine mount beam 31, bleed air conditioning system 234, and out pylon16.

Vibration isolating elements 254 connect bleed valve module 244 to asupport structure, for example, engine mount beam 31 as illustrated inFIG. 3, an internal structural framework (not shown) within pylon 16, ora mechanical support (not shown) for a rigid-walled duct, for example,fan air plenum 232. Bleed valves 256 a-256 c are connected to pipe 252such that bleed valve 256 a (High Pressure Valve) controls the flow ofbleed air (B) from high pressure bleed air line 30 into pipe 252, bleedvalve 256 b (Pressure Regulating Valve) controls the flow of bleed airthrough pipe 252 to un-cooled bleed air line 240, and bleed valve 256 c(Overpressure Valve) provides overpressure control between bleed valve256 b and un-cooled bleed air line 240. Pneumatic actuators 258 a-258 care attached to bleed valves 256 a-256 c to actuate bleed valves 256a-256 c.

Pneumatic control lines 248 a-248 c connect torque motors 264 a-264 c ofpneumatic valve controller 270 to pneumatic actuators 258 a-258 c.Pneumatic supply line 250 connects torque motors 264 a-264 c withinpneumatic valve controller 270 to a supply of pressurized air. Pneumaticsupply line 250 may connect to a single pressurized air supply point,e.g., pipe 252 between bleed valve 256 a and bleed valve moduleconnection 260 a, which supplies high pressure air, as shown in FIG. 4.The use of high pressure air permits the use of smaller pneumaticactuators 258 a-258 c. Alternatively, pneumatic supply line 250 mayconnect to multiple pressurized air supply points, e.g., the housing ofbleed valve 256 a to supply pressurized air to bleed valve 256 a, thehousing of bleed valve 256 b to supply pressurized air to bleed valve256 b, and the housing of bleed valve 256 c to supply pressurized air tobleed valve 256 c. If desired for compatibility with torque motors 264a-264 c, the supply of pressurized air may be cooled by a heat exchangercooled by a fan air flow (not shown). Bleed air pressure sensors 262a-262 b are connected to pipe 252 such that bleed air pressure sensor262 a (High Stage Pressure Sensor) senses pressure in pipe 252 betweenbleed valve 256 a and bleed valve 256 b, and bleed air pressure sensor262 b (Manifold Pressure Sensor) senses pressure in pipe 252 betweenbleed valve 256 b and bleed valve 256 c. Valve position sensors 274a-274 c connect to corresponding bleed valves 256 a-256 c to measure thepositions of bleed valves 256 a-256 c. Torque motors 264 a-264 c, bleedair pressure sensors 262 a-262 b, and valve position sensors 274 a-274 care electrically connected to a bleed system controller (not shown).

Fan air plenum 232 is as described in reference to FIG. 1 for fan airplenum 32, but with the additional feature of fan air duct 272 toconnect fan air plenum 232 to cooling shroud 276. Cooling shroud 276 isconnected to pipe 252 and at least partially surrounds thetemperature-sensitive electrical control elements of pneumatic valvecontroller 270, including torque motors 264 a-264 c, bleed air pressuresensors 262 a-262 b, and valve position sensors 274 a-274 c.

In operation, bleed air conditioning system 234 supplies cooled bleedair at a desired pressure in response to electronic control signals fromthe bleed system controller directed to torque motors 264 a-264 c ofpneumatic valve controller 270. Torque motors 264 a-264 c permit aportion of supply air from pneumatic supply line 250 to pressurizepneumatic control lines 248 a-248 c sufficiently to cause pneumaticactuators 258 a-258 c to open or close bleed valves 256 a-256 c asneeded to achieve the bleed air pressure required by the air managementsystem. For example, when bleed air is desired at pressures less thanthat of intermediate pressure bleed air line 28, torque motor 264 amodulates the supply air from pneumatic supply line 250 to pressurizepneumatic control line 248 a such that pneumatic actuator 258 a closesbleed valve 256 a, preventing high pressure air from flowing throughbleed valve module 244. Bleed air pressure is provided by intermediatepressure bleed air line 28 and controlled by modulating bleed valve 256b by torque motor 264 b via pneumatic control line 248 b and pneumaticactuator 258 b. When bleed air pressures required by the bleed systemcontroller exceed the air pressure available from intermediate pressurebleed air line 28, electronic control signals are sent to torque motor264 a to modulate the supply air to pneumatic actuator 258 a viapneumatic control line 248 a to begin opening bleed valve 256 a. Openingpressure bleed valve 256 a produces pressure in pipe 252 that is higherthan that in intermediate pressure bleed air line 28, causingintermediate pressure check valve 242 to close. Bleed air pressure isprovided by high pressure bleed line 30 and controlled by modulatingbleed valve 256 b by torque motor 264 b via pneumatic control line 248 band pneumatic actuator 258 b. Should a failure occur in the operation ofbleed valves 256 a-256 b, the bleed system controller signals torquemotor 264 c to modulate the supply air to pneumatic actuator 258 c viapneumatic control line 248 c to close bleed valve 256 c and protectsystems downstream of bleed valve module 244.

Un-cooled bleed air flows from bleed valve module 244 into un-cooledbleed air line 240 and into precooler 238. The bleed air is cooled as itflows through precooler 238 by heat transfer to fan air also flowingthrough precooler 238. The heat transfer is by conduction through a heatexchange surface of relatively large area, and by convection to and fromthe heat exchange surface by the bleed air flow and the fan air flow,respectively. At no point in precooler 238 do the bleed air and fan airflows mix. The cooled bleed air flows from precooler 238 into cooledbleed air line 36 and on to the variety of aircraft systems for whichthe aircraft air management system supplies bleed air (not shown).

Bleed air pressure sensors 262 a-262 b provide bleed air pressureinformation to the bleed system controller such that the bleed systemcontroller can determine the electronic control signals to send totorque motors 264 a-264 c to achieve the desired bleed air pressure frombleed air conditioning system 234. Valve position sensors 274 a-274 cdirectly measure the positions of bleed valves 256 a-256 c to providevalve position information to the bleed system controller such that thebleed system controller can more quickly and accurately adjust torquemotors 264 a-264 c to produce the desired bleed air pressure. By closelycoupling the feedback control information provided by valve positionsensors 274 a-274 c with the accurate adjustment of torque motors 264a-264 c, the bleed system controller provides better control withreduced control oscillations. Reducing control oscillations furtherenhances component reliability and lifetime by reducing the adjustmentsrequired of bleed valves 256 a-256 c, which reduces wear on bleed valves256 a-256 c.

The temperature-sensitive electrical control elements of pneumatic valvecontroller 270, including torque motors 264 a-264 c, bleed air pressuresensors 262 a-262 b, and valve position sensors 274 a-274 c, areprotected from the extreme temperatures that are present in the vicinityof bleed valve module 244 by cooling shroud 276. Cool fan air (F) flowsfrom fan air plenum 232 into fan air duct 272 and into cooling shroud276. As the cool fan air circulates within cooling shroud 276, heat istransferred from torque motors 264 a-264 c, bleed air pressure sensors262 a-262 b, and valve position sensors 274 a-274 c by convective heattransfer into the cool fan air flow. Fan air flow out of cooling shroud276 and expelled outside of the aircraft, carrying the transferred heatoverboard.

As noted above, bleed valves 256 a-256 c and pneumatic actuators 258a-258 c are all attached to pipe 252 of bleed valve module 244. Aplurality of vibration isolating elements 254 connect bleed valve module244 to a support structure, as described above, to isolate pipe 252 andall components connected to pipe 252 from vibration. This vibrationisolation serves to enhance the reliability of the components connectedto pipe 252. Vibration isolating element 254 is any type of vibrationisolating device, for example, an elastomeric material, damped spring,or a magneto-rheological fluid.

The embodiment described in reference to FIGS. 3 and 4 has all of theadvantages of the embodiment described above in reference to FIG. 2,including the modular nature of bleed valve module 244 which permitsfast and efficient servicing of bleed valve module 244 to help minimizeaircraft downtime and the vibration isolation of bleed valves 256 a-256c and pneumatic actuators 258 a-258 c from harmful vibration effects.The embodiment of FIGS. 3 and 4 also has the advantage of positioningpneumatic valve controller 270 adjacent to bleed valve module 244 suchthat the temperature-sensitive electrical control elements of pneumaticvalve controller 270 are closely connected to the bleed valve module244, providing many performance and reliability enhancements. This ismade possible by at least partially surrounding thetemperature-sensitive electrical control elements by cooling shroud 276and directing cool fan air through cooling shroud 276. By positioningtorque motors 264 a-264 c close to pneumatic actuators 258 a-258 c,pneumatic control lines 248 a-248 c are even shorter than the embodimentof FIG. 2, further reducing the performance degradation associated withlonger pneumatic control line lengths. Valve position sensors 274 a-274c can be employed close to bleed valves 256 a-256 c, providing closelycoupled feedback to the bleed system controller, thereby reducingcontrol oscillations and the corresponding wear on bleed valves 256a-256 c, in addition to providing more precise valve position control.Finally, locating bleed air pressure sensors 262 a-262 b close to bleedvalve module 244 eliminates the need for pressure impulse lines totransmit pressure within pipe 252 to bleed air pressure sensors 262a-262 b, increasing the responsiveness and accuracy of the bleed airpressure information sent to the bleed system controller.

The above embodiments are illustrated with two pressure sensors, a highstage pressure sensor and a manifold pressure sensor. It is understoodthat the invention encompasses embodiments with only a manifold pressuresensor. For ease of illustration, all valves, actuators, and sensors inthe above embodiments are depicted as identical to each other, but it isunderstood that the invention encompasses embodiments in which varietiesof valve types, actuator types and sensor types are employed. Forexample, an overpressure valve may be of the type that fails closed anda pressure regulating valve and a high pressure valve may be of the typethat fails open.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

The invention claimed is:
 1. A bleed valve control system for use in agas turbine engine having a fan and a fan air flow path that directs fanair flow and includes a fan air plenum, the bleed valve control systemcomprising: a fan air duct that receives and directs fan air flow and isconnected to the fan air plenum; a bleed valve module comprising: ableed air pipe for containing a flow of bleed air from a compressor, thebleed air pipe comprising a plurality of inlets and an outlet; a firstbleed valve connected to the bleed air pipe between a first inlet andthe outlet; and a first pneumatic actuator connected to the first bleedvalve; a cooling shroud mounted on the bleed air pipe, the coolingshroud comprising: a cooling air inlet connected to the fan air duct;and a cooling air outlet in fluid communication with the cooling airinlet and the outlet of the bleed air pipe; and a pneumatic valvecontroller located within the cooling shroud, the pneumatic valvecontroller comprising: a first bleed air pressure sensor connected tothe bleed air pipe between the first bleed valve and the outlet of thebleed air pipe; and a first torque motor connected to the firstpneumatic actuator by a first pneumatic control line; wherein thecooling air inlet and the cooling air outlet of the cooling shroud arepositioned to direct a cooling flow of fan air over the pneumatic valvecontroller.
 2. The bleed valve control system of claim 1, wherein thebleed air pipe outlet is in fluid communication with a pre-cooler toprovide bleed air to be cooled by the pre-cooler, the pre-cooler beingcooled by air flowing through the fan air plenum.
 3. The bleed valvecontrol system of claim 1, wherein the pneumatic valve controllerfurther comprises: a first valve position sensor connected to the firstbleed valve.
 4. The bleed valve control system of claim 1, wherein thebleed valve module further comprises: a second bleed valve connected tothe bleed air pipe between the outlet of the bleed air pipe and thefirst bleed valve; and a third bleed valve connected to the bleed airpipe between the second bleed valve and the outlet of the bleed airpipe.
 5. The bleed valve control system of claim 4, wherein thepneumatic valve controller further comprises: a second bleed airpressure sensor connected to the bleed air pipe between the second bleedvalve and the third bleed valve.
 6. The bleed valve control system ofclaim 4, wherein the pneumatic valve controller further comprises: asecond valve position sensor connected to the second bleed valve; and athird valve position sensor connected to the third bleed valve.
 7. Thebleed valve control system of claim 4, wherein the bleed valve modulefurther comprises: a second pneumatic actuator connected to the secondbleed valve to actuate the second bleed valve; and a third pneumaticactuator connected to the third bleed valve to actuate the third bleedvalve.
 8. The bleed valve control system of claim 7, wherein thepneumatic valve controller further comprises: a second torque motorconnected to the second pneumatic actuator by a second pneumatic controlline; and a third torque motor connected to the third pneumatic actuatorby a third pneumatic control line.
 9. A bleed valve control system foruse in a gas turbine engine having a fan and a fan air flow path thatdirects fan air flow and includes a fan air plenum, the bleed valvecontrol system comprising: a fan air duct that receives and directs fanair flow and is connected to the fan air plenum; a bleed valve modulecomprising: a bleed air pipe for containing a flow of bleed air from acompressor, the pipe comprising a plurality of inlets and an outlet; afirst bleed valve connected to the bleed air pipe between a first inletand the outlet of the bleed air pipe; and a first pneumatic actuatorconnected to the first bleed valve; a cooling shroud mounted on thebleed air pipe, the cooling shroud comprising: a cooling air inletconnected to the fan air duct; and a cooling air outlet in fluidcommunication with the cooling air inlet and the outlet of the bleed airpipe; and a pneumatic valve controller located within the coolingshroud, the pneumatic valve controller comprising: a first torque motorconnected to the first pneumatic actuator by a first pneumatic controlline; and a first valve position sensor connected to the first bleedvalve; wherein the cooling air inlet and the cooling air outlet of thecooling shroud are positioned to direct a cooling flow of fan air overthe pneumatic valve controller.
 10. The bleed valve control system ofclaim 9, wherein the outlet of the bleed air pipe is in fluidcommunication with a pre-cooler to provide bleed air to be cooled by thepre-cooler, the pre-cooler being cooled by air flowing through the fanair plenum.
 11. The bleed valve control system of claim 9, wherein thebleed valve module further comprises: a second bleed valve connected tothe bleed air pipe between the outlet of the bleed air pipe and thefirst bleed valve; and a third bleed valve connected to the bleed airpipe between the second bleed valve and the outlet of the bleed airpipe.
 12. The bleed valve control system of claim 11, wherein thepneumatic valve controller further comprises: a second valve positionsensor connected to the second bleed valve; and a third valve positionsensor connected to the third bleed valve.
 13. The bleed valve controlsystem of claim 11, wherein the bleed valve module further comprises: asecond pneumatic actuator connected to the second bleed valve; and athird pneumatic actuator connected to the third bleed valve.
 14. Thebleed valve control system of claim 13, wherein the pneumatic valvecontroller further comprises: a second torque motor connected to thesecond pneumatic actuator by a second pneumatic control line; and athird torque motor connected to the third pneumatic actuator by a thirdpneumatic control line.